Activities

Activity 1: Testing Essential Growth Factors

Aim: To understand the role of sunlight and water in plant growth.

Materials:

• Three similar potted saplings (A, B, and C).

Procedure:

1. Pot A: Keep in direct sunlight with regular watering.
2. Pot B: Keep in direct sunlight without watering.
3. Pot C: Keep in the dark with regular watering.
4. Observe for two weeks.

Observation:

• Pot A grows healthy. Pot B dies (lack of water). Pot C becomes pale and weak (lack of sunlight).

Conclusion: Both sunlight and water are essential for the healthy growth of plants.

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Activity 2: Starch Test in a Leaf

Aim: To demonstrate the presence of starch in a leaf.

Materials:

• Green leaf, alcohol, water, beaker, iodine solution.

Procedure:

1. Boil the leaf in water to soften it.
2. Place the leaf in a test tube with alcohol and boil it in a water bath until it becomes colorless.
3. Add iodine solution to the decolorized leaf.

Observation: The leaf turns blue-black.

Conclusion: Leaves prepare and store food in the form of starch.

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Activity 3: Testing the Role of CO2

Aim: To prove that carbon dioxide is necessary for photosynthesis.

Materials:

• Potted plant, wide-mouthed bottle, caustic soda (NaOH).

Procedure:

1. Keep the plant in the dark for 48 hours to destarch it.
2. Place half of a leaf inside a bottle containing caustic soda (which absorbs CO2).
3. Keep the set-up in sunlight for 4-5 hours.
4. Test the leaf for starch.

Observation: Only the part outside the bottle (which had access to CO2) turns blue-black.

Conclusion: Carbon dioxide is an essential raw material for photosynthesis.

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Activity 4: Release of Oxygen during Photosynthesis

Aim: To demonstrate that plants release oxygen in the presence of sunlight.

Materials:

• Water plant (e.g., Hydrilla), funnel, test tube, beaker of water.

Procedure:

1. Place the water plant under an inverted funnel in a beaker.
2. Invert a test tube full of water over the stem of the funnel.
3. Keep the set-up in bright sunlight.

Observation: Air bubbles rise and accumulate in the test tube. Testing with a glowing splinter (it bursts into flame) confirms the gas is oxygen.

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Activity 5: Visualising Water Transport (Xylem)

Aim: To show how water moves through the xylem.

Materials:

• White flower twig (e.g., sadabahar), red ink, glass tumbler.

Procedure:

1. Place the twig in a tumbler containing water mixed with red ink.
2. Leave it for 24 hours.

Observation: The white flowers and leaf veins develop red streaks. A cross-section of the stem shows red spots in the xylem region.

Conclusion: Xylem is responsible for the upward transport of water and minerals in plants.